Get this on sale only if you are a fan of their previous games, because sadly Steel Mantis dropped the ball in their shoot em up implementation.
The game features all the classic pitfalls of bad shmups:
-Gigantic player hitbox
-Hard to see enemy projectiles: same color as background, the effects from your weapon obscure everything, foreground obstructs vision, you name it.
-Surprise enemy spawns from the back/below for nice BS deaths
-2.5D shenanigans: enemies/projectiles from z axis, sudden camera rotations that disorient you while you're trying to dodge, etc.
The game promotes going melee, which leads to getting shot in the face with no time to react. Also many actions (like melee and some guns) mess with your movement speed in weird ways, which doesnt feel good in a shmup game which should be all about precision.
The worst sin, though, is how boring it is due to the very bad pacing. 99% of the time you're just cruising through enemies that fly into your shots, until you run into a BS death (see list above). There is no constant sense of tension and danger. Also you have infinite continues and frequent checkpoints, which make the stakes even lower as death means nothing. It's easy to just plow through the game even in hard mode, but, like beating an old arcade game by feeding endless credits, it's not rewarding. Trying to 1cc or minimize deaths, on the other hand, is a recipe for insanity.
There are a couple of good things. The art and style is incredible, both in design and technically, and is the highlight of the game. Also there is great variety of weapons which can give the game some replay value if you're willing to keep playing given all I explained above.
Edit/disclaimer after reading other reviews: I played the game on hard (2 hp) from the get go, because I like challenge and I think it's often the way to put game design to the test. On normal or easy you can probably just breeze through the game tanking the BS and enjoying the visuals. Many people seem to have had a great time with that. For me it would just be more boring.